TWI804941B - Current sensor - Google Patents

Abstract

In the current sensor of the invention, a magnetic conductor surrounds a conductor under test, and two terminals of the magnetic conductor form an air gap. A current on the conductor under test generates magnetic flux on the magnetic conductor, and a sensing element is disposed in the air gap for sensing the current according to the magnetic flux. Two grooves are respectively formed on two sides of the air gap. Since the magnetic resistance between the middle parts of the two grooves is higher than the magnetic resistance between the sides of the two grooves, the range of the high magnetic distribution is wider. Therefore, even if the sensing element is slightly off the predetermined center position due to assembly errors, the magnetic flux can be still sensed, which means the range of allowing the sensing element to be installed can be increased.

Description

current sensor

The present invention relates to a current sensor, especially a current sensor in which grooves are formed on both sides of the air gap of the magnetizer to improve the distribution of magnetic flux.

In the related fields of current sensors, the sensing element can be used to detect the intensity of the magnetic induction generated by the conductor under test, so as to detect the current value on the conductor under test.

However, if there is a slight error in the position of the sensing element, the accuracy of sensing will drop sharply. In other words, the position of the sensing element must be very precise, otherwise the detection result will be inaccurate. The reason for the above problems is that in the distribution of the magnetic flux generated by the conductor under test, the range of the magnetic flux within the allowable error is very narrow. For example, in practice, the allowable error of the magnetic flux is less than 0.1% of the highest magnetic flux. range will not be accurately sensed.

Since the sensing element must be placed in a range with a high magnetic flux, the magnetic flux can be accurately induced, so the range with a high magnetic flux is narrow, which will result in a small space for placing the sensing element, which makes it difficult to assemble and install the sensing element. , the allowable error is very small, which leads to increased difficulty of assembly, and it is difficult to improve the assembly yield.

The embodiment provides a current sensor, which includes a magnetic conductor and a sensing element. The magnetic conductor is used to surround a tested conductor, and a current on the tested conductor generates magnetic flux on the magnetic conductor. The magnetizer has an air gap, a first end and a second end, wherein the air gap is located on the magnetizer, the first end is located on a first side of the air gap and has a first groove, and the The second end is located on a second side of the air gap opposite to the first side and has a second groove. The sensing element is arranged in the air gap, for according to the The magnetic flux generated by the magnetizer induces the current.

100,500,600,700: current sensor

110,610,710: magnetizer

1101, 1102: terminal

1101a, 1101b, 1102a, 1102b, 115a, 115b: side

115: air gap

120: sensing element

150: Conductor under test

310,320,410,420,430,440,450: curve

C1: current

CT1, CT2: center of circle

D1, D2: distance

F: reference surface

L1, L2: axis

R, Ra, Rb: range

R1, R2: radius

SS: short side

SL: long side

G1: first groove

G2: second groove

Fig. 1 is a three-dimensional schematic diagram of a current sensor with a magnetic conductor in an embodiment.

Figure 2 is a front view of the current sensor in Figure 1.

Figure 3 is the distribution curve of the magnetic flux generated by the current on the conductor under test.

FIG. 4 is the measured magnetic flux distribution diagrams after the arc trimming operation is performed with different radii to produce different grooves in the embodiment.

FIG. 5 is a three-dimensional schematic diagram of a current sensor in another embodiment.

FIG. 6 is a schematic diagram of a current sensor in another embodiment.

FIG. 7 is a schematic diagram of a current sensor in another embodiment.

FIG. 1 is a three-dimensional schematic diagram of a current sensor 100 in an embodiment. The current sensor 100 may include a magnetizer 110 and a sensing element 120 . The magnetic conductor 110 may be a ring-shaped magnetic conductor. The magnetic conductor 110 is used to surround the tested conductor 150 . The current C1 on the conductor under test 150 can generate a magnetic flux on the magnetic conductor 110 . The magnetic conductor 110 has an air gap 115 , a first end 1101 and a second end 1102 . The air gap 115 is located on the long side SL of the magnetizer 110 . The first end 1101 is located at the first side 115a of the air gap 115 and has a first groove G1. The second end 1102, located on the second side 115b of the air gap 115 opposite to the first side 115a, has a second groove G2. The sensing element 120 is disposed in the air gap 115 for inducing the current C1 according to the magnetic flux generated by the magnetic conductor 110 . For example, the sensing element 120 can be a Hall sensing element for converting the magnetic flux into a voltage signal, and the voltage signal can be used to measure the current C1. The magnetizer 110 can form a reference plane F, and the measured conductor 150 can penetrate the reference plane F of the magnetizer 110 along the normal line of the reference plane F (that is, the axis L1), and the vertical axis perpendicular to the normal line of the reference plane F ( That is, axis L2) can pass Through the air gap 115.

The shapes of the first groove G1 and the second groove G2 can be adjusted according to requirements. For example, as shown in FIG. 1, the first groove G1 and the second groove G2 of the current sensor 100 can be curved. shaped groove.

If the axis L1 is defined as the front-back direction, FIG. 2 can be a front view of the current sensor 100 in FIG. 1 . The first groove G1 can be generated by performing a first arc trimming operation on the first end 1101 according to the first center CT1 and the first radius R1 , and the circle corresponding to the first arc trimming operation can be parallel to the reference plane F. The second groove G2 can be generated by performing a second arc trimming operation on the second end 1102 according to the second center CT2 and the second radius R2 , and the circle corresponding to the second arc trimming operation can be parallel to the reference plane F. In other words, as shown in Fig. 2, viewed along the direction of the axis L1, the arc-shaped groove produced by the arc trimming operation can be seen.

The current sensor 100 can improve the magnetic flux distribution in the direction of the axis L2, so that the range of high magnetic flux distribution is wider, so that even if the sensing element 120 is slightly shifted from the predetermined center position due to assembly errors, it can still sense less than The magnetic flux within a certain error is to increase the range that allows the sensing element 120 to be set, as described below.

FIG. 3 is a graph showing the distribution of the magnetic flux generated by the current C1 on the conductor 150 under test in FIG. 1 . In Fig. 3, the curve 310 is the distribution curve of the magnetic flux measured by the above-mentioned first end 1101 and the second end 1102 without the groove, and the curve 320 is the distribution curve of the above-mentioned first end 1101 and the second end 1102 with the groove The distribution curve of the measured magnetic flux.

The vertical axis of Fig. 3 may correspond to magnetic flux, and the horizontal axis may be parallel to axis L2 to correspond to position in space. 0.00% on the vertical axis of Figure 3 may correspond to the highest magnetic flux, while values below 0.00% correspond to magnetic fluxes below the highest magnetic flux. On the horizontal axis of Figure 3, the 0% position can correspond to the center line position of the first end 1101 and the second end 1102 on the axis L2, and the 100% position can correspond to the position of the first end 1101 and the second end 1102 on the axis L2. The position away from the measured object 150, and -100% can correspond to the position on the axis L2 where the first end 1101 and the second end 1102 are closest to the measured object 150; in other words, -100% of the horizontal axis in Fig. 3 To 100%, it can correspond to the range R in Figure 2.

As shown in the curve 310, the range Ra corresponding to the highest magnetic flux and the variation of the highest magnetic flux is less than 0.1%, accounts for about 19.9% of the range R, including 11.3% of the deviation from the center point of the range R to the direction of the tested conductor 120 And an 8.6% shift in the opposite direction. In other words, the position of the sensing element 120 on the axis L2 should be set within the range Ra to induce a higher magnetic flux and maintain detection accuracy.

As shown in the curve 320, the range Rb corresponding to the highest magnetic flux and the variation of the highest magnetic flux is less than 0.1%, accounts for about 62.8% of the range R, including 33.4% of the deviation from the center point of the range R to the direction of the tested conductor 120 , and a 29.4% shift in the opposite direction. In other words, the position of the sensing element 120 on the axis L2 should be set within the range Rb to induce a higher magnetic flux and maintain detection accuracy.

Comparing the curve 310 and the curve 320, it can be seen that when the first end 1101 and the second end 1102 have grooves, the maximum magnetic flux and the range in which the variation of the maximum magnetic flux is less than a predetermined ratio (such as 0.1%) can be expanded, such as in the present invention In one of the embodiments, it can be increased from the range Ra (19.9%) to the range Rb (62.8%), which is increased by 3.15 times. Therefore, the range of positions where the sensing element 120 is allowed to be disposed can be expanded, thereby reducing the requirement and difficulty of precision during assembly, and improving the yield rate of assembly. The numbers and curves in FIG. 3 are just examples to help understand the embodiment, but the embodiment is not limited thereto.

The total magnetic flux corresponding to the curve 310 and the curve 320 is substantially equal, however, by using the first groove G1 and the second groove G2, the distribution of the magnetic flux can be changed. The distance D1 between the middle of the first groove G1 and the middle of the second groove G2 is greater than the distance D2 between the two sides of the first groove and the two sides of the second groove; The middle is not limited to the position in the middle, but refers to the position between the two sides. Therefore, the reluctance between the middle of the first groove G1 and the middle of the second groove G2 is greater than the reluctance between two sides of the first groove G1 and two sides of the second groove G2 . Therefore, the distribution of the magnetic flux can be adjusted so that the magnetic flux is more distributed to both sides, so that the distribution curve of the magnetic flux is flatter and wider near the highest point, so as to reduce the accuracy requirements and difficulty during assembly.

According to an embodiment, as shown in FIG. 2, the first end 1101 of the magnetizer 110 may include a first side 1101a and a second side 1101b, the first side 1101a is closer to the conductor 150 under test than the second side 1101b, and the first The distance between the circle center CT1 and the first side 1101a is smaller than the distance between the first circle center CT1 and the second side 1101b; in other words, the first circle center CT1 may not be located at the center line of the first end 1101, but may be set closer to the conductor under test 150 . This can further improve the flux distribution, as explained below.

As shown in the curve 310 of Fig. 3, when the groove of the magnetizer 110 is not used to adjust the magnetic flux distribution, the highest magnetic flux is not located at the centerline position of the first end 1101 (that is, at 0% of the horizontal axis), but Compared with the position of the center line, it is slightly deviated and located in the negative direction of the horizontal axis, because the magnetic flux near the conductor 150 under test is higher. Therefore, when the arc trimming operation is performed to design the groove, the first circle center CT1 can be set slightly closer to the conductor 150 under test, so that the concave part of the groove (that is, the place with greater magnetic resistance) corresponds to the adjusted The position of higher magnetic flux before is used to provide more adjustments to the distribution of magnetic flux, so that the adjusted higher magnetic flux can be distributed more widely in space. Similarly, the second end 1102 may include a first side 1102a and a second side 1102b, the first side 1102a is closer to the conductor under test 150 than the second side 1102b, and the distance between the second circle center CT2 and the first side 1101a may be less than The distance between the second circle center CT2 and the second side 1102b is such that the second circle center CT2 is closer to the conductor 150 under test, so as to better improve the magnetic flux distribution.

FIG. 4 is the measured magnetic flux distribution diagrams after the arc trimming operation is performed with different radii to produce different grooves in the embodiment. The vertical axis and horizontal axis of Fig. 4 can be as Fig. 3, so it will not be repeated. Compared with the magnetic flux within the allowable error without arc trimming, the arc trimming is carried out with a reference radius, so that the distance from the center is more than 3 times and the magnetic flux is still within the allowable error. The corresponding change of the magnetic flux curve is the corresponding curve 430 . That is to say, when the arc trimming operation is not performed, that is, when there is no groove at both ends of the magnetizer 110, the distribution of the magnetic flux has an allowable error (for example, ±0.1% or less of the maximum magnetic flux) in an original high flux region. ); and when using the reference radius to perform the arc trimming operation to produce grooves at both ends of the magnetizer 110, the distribution of the magnetic flux has an allowable error in a reference high flux interval, and the space in the reference high flux interval The width of the location (horizontal axis) may be at least 3 times wider than the width of the original high flux region. Accordingly, a reference radius can be defined, wherein curve 410 corresponds to a radius where the reference radius is reduced by 11.43%, curve 420 corresponds to a radius where the reference radius is reduced by 5.7%, curve 440 corresponds to a radius where the reference radius is increased by 5.7%, and curve 450 corresponds to on benchmark Radius increased by 11.43%.

As shown in Figure 4, if the radius of the arc trimming operation is less than 90% of the reference radius (for example, curve 410), then on the axis L2, the high flux range of the magnetic flux distribution is too narrow, and it is impossible to increase the set sensing Allowable range of component 120. If the radius of the arc trimming operation is greater than 110% of the reference radius (for example, curve 450), then on the axis L2, the middle part of the high magnetic flux interval of the magnetic flux distribution is concave, and the magnetic flux in the middle part of the two ends is too low. Therefore, preferably, the radius of the arc trimming operation for the first end 1101 and the second end 1102 can be set within a specific length range of the reference radius (for example, 90%~110% of the reference radius), and the values in Figure 4 are only For example, to help explain the embodiment, the embodiment is not limited thereto.

FIG. 5 is a three-dimensional schematic diagram of a current sensor 500 in another embodiment. The current sensor 500 may be similar to the current sensor 100 in FIG. 1 , but the orientation of the grooves is different. In Figure 5, the first groove G1 can be generated by performing the first arc trimming operation on the first end 1101 according to the first center CT1 and the first radius R1, and the circle corresponding to the first arc trimming operation can be perpendicular to the reference plane F. The second groove G2 can be generated by performing a second arc trimming operation on the second end 1102 according to the second center CT2 and the second radius R2 , and the circle corresponding to the second arc trimming operation can be perpendicular to the reference plane F. In other words, as shown in Fig. 2, looking along the direction of the axis L2, the arc-shaped groove produced by the trimming operation can be seen.

The current sensor 500 can improve the magnetic flux distribution in the direction of the axis L1, so that the range of high magnetic flux distribution is wider, so as to increase the range where the sensing element 120 is allowed to be disposed. The principle of the current sensor 500 is similar to that of the current sensor 100 , so it will not be described again. As described in FIG. 4 , the radius of the arc trimming operation of the current sensor 500 can be set within a specific length range of the reference radius.

According to an embodiment, the arc trimming operations in both directions shown in FIG. 1 and FIG. 5 can be performed to generate grooves, thereby improving the magnetic flux distribution in the direction of the axis L1 and the axis L2.

n。同理，第二凹槽G2亦可根據n個圓心及m個半徑對第一端1101執行n次修弧操作而產生。採用多次修弧，可進一步調整凹槽形狀，以進一步改善調整磁通分佈的結果。 In Fig. 1 and Fig. 5, each groove is generated by performing an arc trimming operation with a single center and a single radius. However, according to an embodiment, each groove can be generated by performing multiple arc trimming operations with multiple centers and multiple radii. For example, the first groove G1 can be generated by performing n times of arc trimming operations on the first end 1101 according to n circle centers and m radii, and n circles corresponding to n arc trimming operations can be parallel to the reference plane F (similar to Figure 1) or perpendicular to the reference plane F (similar to Figure 5), where n and m are positive integers and m

n. Similarly, the second groove G2 can also be generated by performing n times of arc trimming operations on the first end 1101 according to n circle centers and m radii. Using multiple arc trimming, the shape of the groove can be further adjusted to further improve the result of adjusting the magnetic flux distribution.

According to an embodiment, in FIG. 1 and FIG. 5 , the distance between the sensing element 120 and the first end 1101 may be substantially equal to the distance between the sensing element 120 and the second end 1102 .

As shown in Figure 1, Figure 2 and Figure 5, the magnetizer 110 has a long side SL and a short side SS, and the air gap 115 is located on the long side SL, therefore, the magnetizer 110 in Figure 1 is a C-shaped magnetizer . FIG. 6 is a front view of a current sensor 600 according to another embodiment. Similar to the current sensors 100 and 500 , the magnetizer 610 of the current sensor 600 also has a long side SL and a short side SS, but the air gap 115 is located on the short side SS, therefore, the magnetizer 610 is a U-shaped magnetizer. The principle and structure of the current sensor 600 are similar to those of the current sensors 100 and 500 , so it will not be described again.

In Fig. 1, Fig. 5, and Fig. 6, the short sides of the magnetizer 110 and the magnetizer 610 can be arc-shaped, so that the magnetizer 110 and the magnetizer 610 have a shape similar to a track and field field; The shapes of the magnetizer 110 and the magnetizer 610 in FIG. 5 and FIG. 6 are just examples. According to the embodiment, under the same volume, the C-shaped magnetizer 110 has a larger current range than the U-shaped magnetizer 610 , is less prone to magnetic saturation, and has better sensing accuracy at low currents.

FIG. 7 is a front view of a current sensor 700 according to another embodiment. Different from the current sensors 100 , 500 and 600 , the magnetic conductor 710 of the current sensor 700 does not distinguish between long sides and short sides, so it has a shape similar to a circle.

Similarly in Fig. 1 and Fig. 5, in the current sensors 600 and 700, the circle corresponding to the arc trimming operation for generating grooves can be parallel or perpendicular to the reference plane F to generate grooves in different directions, so as to The distribution of the magnetic flux in the direction of the axis L2 or the direction of the axis L1 is improved.

In general, by forming grooves at both ends of the magnetizers 110, 610, and 710, the distribution of the magnetic flux in the direction of the axis L2 or the direction of the axis L1 can be improved, and the range of the high magnetic flux on the distribution curve can be wider to increase the available The range of the sensing element 120 is set, so as to reduce the requirement for assembly accuracy and improve the assembly yield.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

100: current sensor

110: magnetizer

1101, 1102: terminal

1101a, 1101b, 1102a, 1102b, 115a, 115b: side

115: air gap

120: sensing element

150: Conductor under test

C1: current

CT1, CT2: center of circle

D1, D2: distance

F: reference surface

L1, L2: axis

R1, R2: radius

SS: short side

SL: long side

G1: first groove

G2: second groove

Claims (10)

A current sensor, comprising: a magnetic conductor, used to surround a tested conductor, a current on the tested conductor generates magnetic flux on the magnetic conductor, the magnetic conductor has: an air gap, located on the magnetic conductor a first end, located on a first side of the air gap, having a first groove; and a second end, located on a second side of the air gap opposite the first side, having a second groove and a sensing element arranged in the air gap for inducing the current according to the magnetic flux generated in the magnetic conductor; wherein the first groove and the second groove are arc grooves. The current sensor according to claim 1, wherein the magnetizer is a ring-shaped magnetizer. The current sensor as claimed in claim 1, wherein the magnetizer has a long side and a short side, and the air gap is located on the long side. The current sensor as claimed in claim 1, wherein the magnetizer has a long side and a short side, and the air gap is located on the short side. The current sensor as claimed in claim 1, wherein: the magnetizer forms a reference surface, the conductor under test passes through the reference surface along a normal line of the reference surface, and is perpendicular to a vertical axis of the normal line through the air gap; the first groove performs a first arc trimming operation on the first end according to a first center and a first radius and the first arc repair operation corresponds to a first circle parallel to the reference plane; and the second groove is performed on the second end according to a second circle center and a second radius The arc trimming operation is generated, and the second arc trimming operation corresponds to a second circle parallel to the reference plane. The current sensor as described in claim 5, wherein the first end includes a first side and a second side, the first side is closer to the conductor under test than the second side, and the first center and The distance between the first side is smaller than the distance between the first center and the second side, and the distance between the second center and the first side is smaller than the distance between the second center and the second side. The current sensor as claimed in claim 1, wherein: the magnetizer forms a reference surface, the conductor under test passes through the reference surface along a normal line of the reference surface, and is perpendicular to a vertical axis of the normal line through the air gap; the first groove is generated by performing a first arc trimming operation on the first end according to a first circle center and a first radius, and the first arc trimming operation corresponds to a first circle The shape is perpendicular to the reference surface; and the second groove is generated by performing a second arc repairing operation on the second end according to a second center and a second radius, and the second arc repairing operation corresponds to a first arc repairing operation Two circles are perpendicular to the reference plane. The current sensor as claimed in claim 5 or 7, wherein: the first radius is between 90% and 110% of a reference radius; wherein when the arc repair operation is not performed, the distribution of the magnetic flux is at a There is an allowable error in the original high magnetic flux interval, and when an arc trimming operation is performed using the reference radius, the distribution of the magnetic flux has the allowable error in a reference high magnetic flux interval, and the reference high magnetic flux interval is at least is three times as wide as the original high-flux region. The current sensor according to claim 1, wherein: the first groove is generated by performing n times of arc repairing operations on the first end according to n circle centers and m radii, and the n times of arc repairing operations correspond to The n circles are parallel to the reference plane; where n and m are positive integers and m

n. The current sensor according to claim 1, wherein: the first groove is generated by performing n times of arc repairing operations on the first end according to n circle centers and m radii, and the n times of arc repairing operations correspond to The n circles are perpendicular to the reference plane; where n and m are positive integers and m

n.

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